Question

Phosphine, an extremely poisonous and highly reactive gas, reacts with oxygen gas to form tetraphosphorus decaoxide and water. ph3(g) + o2(g) → p4o10(s) + h2o(g) [unbalanced] calculate the mass of p4o10(s) formed when 225 g of ph3 reacts with excess oxygen.

Answer 1

The molar mass of PH3 is 34 g/mol, therefore the moles is:

moles PH3 = 225 g / (34 g/mol)

moles PH3 = 6.62 mol

 

The balanced equation is:

4PH3(g) + 8O2(g) → P4O10(g) + 6H2O

 

We see that 4 mol of PH3 is required for every mol of P4O10, therefore the number of moles of P4O10 is:

moles P4O10 = 6.62 mol * (1/4)

moles P4O10 = 1.65 mol

 

The molar mass of P4O10 is 283.89 g/mol, so the mass is:

mass P4O10 = 1.65 mol * 283.89 g/mol

mass P4O10 = 469.67 grams ~ 470 grams